1. Technical Field
The present invention relates to a transmitter to be used in a mobile communication system or the like and, more particularly, to a transmitter for effectively reducing a peak power to occur in a signal to be transmitted.
2. Background Art
In a transmitter of a mobile communication system for performing radio communications by adopting the code division multiple access (CDMA) system, it is performed by a digital modulation unit to process the transmission target signal (or the signal to be transmitted).
In the digital modulation unit, for example, a plurality of N-number carrier signals are individually wave-shaped by wave-form shaping filters and are then modulated by digital orthogonal modulation units. These modulation results are added for the N-number carriers by adders and are outputted.
In this transmitter, for the intermediate frequency signals (i.e., the output signals from those adders) after the individual carrier synthesizations, the peripheries of peaks are multiplied by a window function thereby to suppress the peaks (as referred to Patent Document 1, for example).
Patent Document 1: JP-A-2005-20505